I just read an interesting review of the new Google Glass, which, by the way, is very, very cool. But that’s beside the point.
The writer had a chance to try out Google Glass, and he wrote a good article. Here’s the article: http://www.sfgate.com/technology/businessinsider/article/I-Just-Tried-On-Google-Glass-And-This-Is-What-It-4347779.php
Now, to the point. The writer has a good grasp of correct comma use, and by correctly using commas, he made his moderately complex sentences easy to read and understand. In fact, I only found three comma errors, a better-than-typical rate for online journalists.
One of the comma errors, though, was so egregious that it deserves some explanation. The writer wrote,
“What I did realize, is that Google needs to offer a solution for individuals who wear glasses.”
The comma error is the comma betwen realize and is. By placing a comma there, the writer breaks Zen Comma rule AJ: No commas between subjects and predicates. When we parse this sentence, we can see how the comma breaks this rule.
The main verb begins the predicate of the sentence. In this sentence, the main verb is “is.” In most sentences, including this one, the subject is just prior to the predicate. In this sentence, the subject is “What I did realize.”
Subject: “What I did realize”
Predicate: “is that Google needs to offer….”
The comma separates the subject from the predicate, and it needs to be removed to make this sentence correct.
Why is this a problem? What’s the purpose of rule AJ?
Commas separate elements in sentences. However, the subject of a sentence must have a main verb to have meaning. Similarly, the predicate has no value, no meaning, unless it has a subject. As such, these two elements of the sentence cannot be separated. They work together to provide meaning.
Because they cannot be separated (or, because they must be together), we don’t separate them with a comma.
Commas Between Subjects and Predicates
“Hey,” you might be thinking, “I see commas between subjects and predicates all the time!” Yes, in some cases, we can have commas between subjects and predicates without breaking Zen Comma rule AJ. Here’s a correct example, also from the article.
“The right side of Glass, where the battery rests, is touch-sensitive.”
When we parse this sentence, we find the following.
Subject: “The right side of Glass”
Predicate: “is touch sensitive.”
Between the subject and predicate, we read the clause “where the battery rests.” This clause is an appositive for “The right side of Glass.” It is surrounded by commas, with the result that two commas are between the subject and predicate. Those commas are required by Zen Comma Rule J: Separate non-restrictive appositives with commas.
If we take out the appositive, we also take out the commas. In other words, the commas are there because of the appositive, not to separate the subject and predicate. In fact, they tell the reader when the appositive begins and ends so that the reader can easily find the predicate and connect it to the subject.
In any case, this is not what is happening in the faulty sentence. The faulty sentences doesn’t have an appositive (or other clause requiring commas) between the subject and predicate. Even if there were a reason for commas, we would need two, not one, commas.
End result: The writer made a comma error. That comma needs to go.